This invention relates to a process for preparing interpolymers of ethylene, at least one or more heteroatom substituted olefin monomers, and optionally carbon monoxide. The process is a high pressure, free radical initiator, polymerization process. The invention also relates to novel ethylene interpolymers having Tm values of at least 50xc2x0 C.
Plastics and elastomers derived from olefins are used in numerous diverse applications, from trash bags to fibers for clothing. Olefin polymers are used, for instance, in injection or compression molding applications, such as extruded films of sheeting, as extrusion coatings on paper, such as photographic paper and thermal and digital recording paper, and the like. Constant improvements in catalysts have made it possible to better control polymerization processes, and thus influence the properties of the bulk material. Increasingly, efforts are being made to tune the physical properties of plastics for lightness, strength, resistance to corrosion, permeability, optical properties, and the like, for particular uses. In addition to chain length and branching, the incorporation of monomers containing functional groups, such as ethers and esters, offers an opportunity to further modify and control the properties of the bulk material. For example, the early transition metal catalyst systems (i.e., Group IV) tend to be intolerant to such functional groups, which often causes catalyst deactivation.
Conventional low density polyethylenes are readily prepared in high temperature, high pressure polymerizations using peroxide initiators.
These high pressure free radical systems can also be used to prepare ethylene copolymers containing functional vinyl monomers, but it is important to note that only a small number of monomers can be polymerized in this high energy (e.g., 200xc2x0 C., 30K psi) process, i.e., vinyl acetate and methyl acrylate.
Certain transition metal catalysts, such as those based on titanium compounds (e.g., TiCl3 or TiCl4) in combination with organoaluminum cocatalysts, are used to make high density polyethylene and linear low density polyethylenes (HDPE ,nd LLDPE, respectively), as well as poly-xcex1-olefins such as polypropylene. These so-called xe2x80x9cZiegler-Nattaxe2x80x9d catalysts are quite sensitive to oxygen, sulfur and Bronsted acids, and thus generally cannot be used to make olefin copolymers with functional vinyl monomers having oxygen, sulfur, or Bronsted acids as functional groups.
Zielger-Natta and metallocene catalyst systems, however, have the drawback that they cannot generally be used in olefin polymerization reactions with functionalized monomers. It is known in the art that homogeneous single site transition metal catalysts generally allow for specific control of catalyst activity through variation of the electronic and steric nature of the ligand. Homogeneous catalysts are known to offer several advantages over heterogeneous catalysts, such as decreased mass transport limitations, improved heat removal, and narrower molecular weight distributions.
None of the references described above disclose the copolymerization of olefins with 3,4-epoxy-1 -butene (hereinafter xe2x80x9cepoxybutenexe2x80x9d), epoxybutene derivatives, and analogs thereof. Epoxybutene is a readily available compound containing two reactive groups: a double bond and an epoxide. By reaction at one or both groups, epoxybutene can easily be converted into a host of compounds.
The preparation of epoxybutene and derivatives thereof, and examples of the same, have previously been described in numerous references, including, but not limited to, U.S. Pat. Nos. 4,897,498; 5,082,956; 5,250,743; 5,315,019; 5,406,007; 5,466,832; 5,536,851; and 5,591,874 which are incorporated herein by reference. Reaction at one or both of these sites affords a host of olefinic derivatives, many of which contain versatile functional groups. Polymerization of epoxybutene has been performed using traditional thermal and free radical initiated reactions, however the pendant epoxide group often does not survive the reaction conditions.
Advances in the polymerization of epoxybutene and its derivatives include the following:
L. Schmerling et al., U.S. Pat. No. 2,570,601 describes the thermal homopolymerization of epoxybutene and the thermal copolymerization of epoxybutene and various vinyl monomers, such as vinyl chloride, vinyl acetate, acrylonitrile, butadiene and styrene.
Polymerization reactions of epoxybutene, in which the epoxide ring is opened to afford polyethers, are known, such as those described in: S. N. Falling et al., U.S. Pat. No. 5,608,034 (1997); J. C. Matayabas, Jr., S. N. Falling, U.S. Pat. No. 5,536,882 (1996); J. C. Matayabas, Jr. et al., U.S. Pat. No. 5,502,137 (1996); J. C. Matayabas, Jr., U.S. Pat. No. 5,434,314 (1995); J. C. Matayabas, Jr., U.S. Pat. No. 5,466,759 (1995); and J. C. Matayabas, Jr., U.S. Pat. No. 5,393,867 (1995).
W. E. Bissinger et al., J. Am. Chem. Soc., 1947, 69, 2955 describes the benzoyl peroxide initiated free radical polymerization of vinyl ethylene carbonate, a derivative of epoxybutene.
Cationic polymerization of vinyl ethers (such as 2,3-dihydrofuran) is known using Lewis acids or proton-containing acids as initiators. These monomers have been shown to polymerize violently through a cationic polymerization mechanismxe2x80x94often at rates orders of magnitude faster than anionic, or free radical polymerizationsxe2x80x94in the presence of both Bronsted and Lewis acids (P. Rempp and E. W. Merrill, xe2x80x9cPolymer Synthesis,xe2x80x9d Huthig and Wepf, 2nd ed, Basel (1991), pp. 144-152). Olefin addition polymerization of vinyl ethers via a transition metal mediated insertion mechanism has not been demonstrated.
In addition, the synthesis of alternating copolymers and terpolymers of olefins and carbon monoxide is of high technical and commercial interest. New polymer compositions, as well as new processes to make polymers derived from olefins and carbon monoxide, are constantly being sought. Perfectly alternating copolymers of xcex1-olefins and carbon monoxide can be produced using bidentate phosphine ligated Pd(II) catalyst systems (Drent et al., J. Organomet. Chem., 1991, 417, 235). These semi-crystalline copolymers are used in a wide variety of applications including fiber and molded part applications. These materials are high performance polymers having high barrier and strength, as well as good thermal and chemical stability.
Alternating copolymerization of olefins and CO using Pd(II) catalysts has been demonstrated by Sen et al., J. Am. Chem. Soc., 1982, 104, 3520; and Organometallics, 1984, 3, 866, which described the use of monodentate phosphines in combination with Pd(NCMe)4 (BF4)2 for the in situ generation of active catalysts for olefin/CO copolymerization. However, these catalyst systems suffer from poor activities and produce low molecular weight polymers. Subsequent to Sen""s early work, Drent and coworkers at Shell described the highly efficient alternating copolymerization of olefins and carbon monoxide using bisphosphine chelated Pd(II) catalysts. Representative patents and publications include: U.S. Pat. No. 4,904,744 (1990); J. Organomet. Chem., 1991, 417, 235; and U.S. Pat. No. 4,970,294 (1990).
Recent advances in olefin/CO copolymerization catalysis include the following:
Brookhart et al., J. Am. Chem. Soc., 1992, 114, 5894, described the alternating copolymerization of olefins and carbon monoxide with Pd(II) cations ligated with 2,2-bipyridine and 1,10-phenanthroline;
Brookhart et al., J. Am. Chem. Soc., 1994, 116, 3641, described the preparation of a highly isotactic styrene/CO alternating copolymer using C2-symmetric Pd(II) bisoxazoline catalysts;
Nozaki et al, J. Am. Chem. Soc., 1995, 117, 991 1, described the enantioselective alternating copolymerization of propylene and carbon monoxide using a chiral phosphine-phosphite Pd(II) complex.
None of these references teach the copolymerization of olefins with carbon monoxide and functionalized olefins, like epoxybutene and related compounds.
U.S. Pat. No. 6,090,900 discloses homopolymers of olefin monomers having polar functional groups, and copolymers of these monomers With each other and With non-polar olefins, and optionally carbon monoxide.
The present invention is directed to interpolymers comprising ethylene, at least one, or more, monomer units selected from heteroatom substituted olefin monomer units derived from a compound of the formula XV. 
wherein E and G represent the same or different heteroatoms selected from oxygen, nitrogen, and sulfur, which are bound to a hydrogen atom, a hydrocarbyl group, or a substituted hydrocarbyl group, or are joined by a linking group; and n is 0 or an integer from 1-20; or 2,3-dihydrofuran, and optionally carbon monoxide. The novel products of the present invention are the interpolymers as described herein that are characterized by having a melting peak temperature (Tm), as determined by the procedure specified herein, of equal to or greater than 50xc2x0 C., preferably from equal to or greater than 50xc2x0 C. to about 115xc2x0 C.
The novel process for preparing the interpolymers comprising ethylene, the at least one or more monomer unit selected from the specified heteroatom substituted olefin monomer unit or 2,3-dihydrofuran, and, optionally, carbon monoxide, including the novel interpolymers of the present invention characterized by having a melting peak temperature (Tm) of equal to or greater than 50xc2x0 C., preferably from equal to or greater than 50xc2x0 C. to about 115xc2x0 C., is comprised as follows. The interpolymers are produced by polymerization of the monomers in any suitable high pressure reactor known for the polymerization of ethylene-containing monomer mixtures, examples of which include autoclaves, tubular reactors and the like. In general, the interpolymerization of the monomers is conducted at a temperature of from about 150xc2x0 C. to about 350xc2x0 C., at a pressure of from about 68 to about 304 MPa""s (about 671 to about 3000 atmospheres), and for a period of time of from about 2 to about 600 seconds. The interpolymerization process is conducted in the presence of at least one, or more, free radical initiators, that are defined as chemical substances that, under the polymerization conditions utilized, initiate chemical reactions by producing free radicals.
The present invention is directed to interpolymers comprising ethylene, at least one, or more, monomer units selected from heteroatom substituted olefin monomer units derived from a compound of the formula XV 
wherein E and G represent the same or different heteroatoms selected from oxygen, nitrogen, and sulfur, which are bound to a hydrogen atom, a hydrocarbyl group, or a substituted hydrocarbyl group, or are joined by a linking group; and n is 0 or an integer from 1-20; or 2,3-dihydrofuran, and optionally carbon monoxide. The novel products of the present invention are the interpolymers as desrcribed herein that are characterized by having a melting peak temperature (Tm), as determined by the procedure specified herein, of equal to or greater than 50xc2x0 C., preferably from equal to or greater than 50xc2x0 C. to about 115xc2x0 C.
The novel process for preparing the interpolymers comprising ethylene, the at least one or more monomer unit selected from the specified heteroatom substituted olefin monomer unit or 2,3-dihydrofuran, and, optionally, carbon monoxide, including the novel interpolymers of the present invention characterized by having a melting peak temperature (Tm) of equal to or greater than 50xc2x0 C., preferably from equal to or greater than 50xc2x0 C. to about 115xc2x0 C., is comprised as follows. The interpolymers are produced by polymerization of the monomers in any suitable high pressure reactor known for the polymerization of ethylene-containing monomer mixtures, examples of which include autoclaves, tubular reactors and the like. In general, the interpolymerization of the monomers is conducted at a temperature of from about 150xc2x0 C. to about 350xc2x0 C., at a pressure of from about 68 to about 304 MPa""s (cabout 671 to about 3000 atmospheres), and for a period of time of from about 2 to about 600 seconds. The interpolymerization process is conducted in the presence of at least one, or more, free radical initiators, that are defined as chemical substances that, under the polymerization conditions utilized, initiate chemical reactions by producing free radicals.
In more detail, the interpolymers comprise from about 0.1 to about 99.9 mol percent (%), preferably about 40 to about 99.9, more preferably about 90 to about 99.9 mol %, ethylene; from about 0.1 to about 99.9 mol percent (%), preferably about 0.1 to about 60, more preferably about 0.1 to about 10 mol %, of the at least one or more monomer units selected from heteroatom substituted olefin monomer units derived from a compound of the formula XV 
wherein E and G represent the same or different heteroatoms selected from oxygen, nitrogen, and sulfur, which are bound to a hydrogen atom, a hydrocarbyl group, or a substituted hydrocarbyl group, or are joined by a linking group; and n is 0 or an integer from 1-20; or 2,3-dihydrofuran; and from about 0 to about 10 mol percent (%) carbon monoxide, all of the amounts based on the total interpolymer.
Exemplary heteroatom substituted olefin monomer units derived from a compound of the formula XV 
include the following: 
wherein R1 and R2 are independently hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or R1 and R2 collectively from a bridging group Y wherein Y is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; R10, R11, and R12 are independently hydrogen, hydrocarbyl, or substituted hydrocarbyl; and Ph is phenyl. Particularly preferred interpolymers of the present invention include ethylene and either vinylethylene carbonate, 2,3-dihydrofuran, 3,4-diacetoxy-1-butene, and 3-butene-1,2-diol, optionally with carbon monoxide.
The novel process for preparing the ethylene interpolymers described herein is further characterized as follows. The interpolymerization process is conducted at a pressure of from about 68 to about 304 MPa""s (about 671 to about 3000 atmospheres), preferably from about 103 to about 241 MPa""s (about 1020 to about 2381 atmospheres), and more preferably from about 138 to about 207 MPa""s (about 1361 to about 2041 atmospheres). The interpolymerization process is conducted at a temperature of from about 150xc2x0 C. to about 350xc2x0 C., preferably from about 150xc2x0 C. to about 250xc2x0 C., and more preferably from about 150xc2x0 C. to about 200xc2x0 C. The interpolymerization process is conducted for a period of time ranging from about 2 to about 600 seconds, preferably from about 30 to 300 seconds, and more preferably from about 30 to about 60 seconds.
The interpolymerization process is conducted in the presence of at least one, or more, free radical initiators. As used herein, a free radical initiator is defined as a chemical substance that, under the polymerization conditions utilized, initiates chemical reactions by producing free radicals. Exemplary free radical initiators, suitable for use in the present process, include the following listed substances.
1. Organic Peroxides such as
The free radical initiator are generally utilized in amounts of from about 1 to about 1000 ppm (parts per million), preferably from about 20 to about 300 ppm, and more preferably from about 50 to about 100 ppm, based on the total weight of the ethylene component of the interpolymer. Mixtures of free radical initiators can be used. The free radical initiators can be introduced into the polymerization process in any manner known in the art.
The polymerization process according to the present invention is conducted in a continuous or batch process manner. Any continuous or batch type process can be used in the practice of the present invention.
The interpolymers of the present invention are useful for one or more of the following: printable film; xe2x80x9cbreathablexe2x80x9d film; adhesive formulations; glass-fiber reinforcement; polymer blends; compatibilizing agents; toughening agent for nylon and similar materials; grafting applications; conducting polymers; plastic plating; ionomers; thermosetting applications; coatings; powder coatingsxe2x80x94flame sprayed polyethylene; engineering plasticsxe2x80x94impact resistant masses; tie-layersxe2x80x94as the carbonate or diacetate copolymers or as their hydrolyzed versions, the diols; urethanes; epoxiesxe2x80x94through the conversion of the carbonate rings into epoxide functionalities; cross-linking agents; molding applications; paper and textile additives; low temperature applications; vulcanization; wax applications; clay filled materials for sound barrier applications; blend components to lower heat seal initiation temperature; oxygen scavenging applications; as polydiols, for polyester or polycarbonate synthesis; may be used with typical additives such as pigments, colorants, titanium dioxide, carbon black, antioxidants, stabilizers, slip agents, flame retarding agents, and the like.
The invention will be more readily understood by reference to the following examples. There are, of course, many other forms of this invention which will become obvious to one skilled in the art, once the invention has been fully disclosed, and it will accordingly be recognized that these examples are given for the purpose of illustration only, and are not to be construed as limiting the scope of this invention in any way. Moreover, all U.S. patents referred to herein are incorporated by reference in their entirety.